Spring structure.



H. H. BUFFUM.

SPRING STRUCTURE. APPLICATION FILED JUNE 10. 1914.

Patented Oct. 26, 1915.

2 SHEETS-SHEET 1.

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Ewe/71,60? ZEBWC6777 H. H. BUFFUM.

SPRING STRUCTURE,

APPLICATION FILED JUNE 10. 1914.

Patented Oct. 26, 1915.

2 SHEETSSHEET 2.

COLUMBIA PLANOCIRAPH conwAsmNc'roN. D. c.

HERBERT I-I. BUFFUM, OF THE WEIRS, NEW HAMPSHIRE.

SPRING STRUCTURE.

Specification of Letters Patent.

Patented Oct. 26, 1915.

Application filed June 10, 1914:. Serial No. 844,204.

I '0 all whom it may concern:

Be it known that I, HERBERT H. BUFFUM, a citizen of the United States,and resident of The Weirs, in the county of Belknap and State of NewHampshire, have invented certain new and useful Improvements in SpringStructures, of which the following is a specification.

This invention relates to vehicle springs and particularly to laminatedleaf springs having their outer ends attached to the wheel axles andtheir inner portions anchored on the vehicle frame. @rdinarily suchsprings are tapered at both ends and have two points of support on theframe. They have come to be known generally as cantaliver springs,although sometimes existing simply as a quarter-elliptic spring providedwith a single anchorage on the frame.

My invention has for its object to divide springs of this generalcharacter into serially-acting sections, the inner section being heldunder permanent initial deflection and remaining inactive under thelighter loads or impacts, while the outer section is free to respond tothese-lighter loads and acts upon the inner section to impart thereto afurther deflection under the heavier loads or impacts. To this end Iprovide the spring with an additional point of support or abutment onthe vehicle frame, located between the axle andthe main point ofanchorage or upward pressure of said spring on the frame, and acting inthe manner stated.

The accompanying drawings show various forms and adaptations of theinvention, which forms and adaptations are illustrated to facilitate anunderstanding and not to limit the invention.

0n the drawings :Figure 1 represents a top plan view of a portion of avehicle equipped with double cantaliver laminated leaf-spring structuresembodying one form of the invention. Fig. 2 represents an elevation,partly in section, of the structure included within the range of line2-2 of Fig. 1. Fig. 3 represents an elevation of the structure includedwithin the range of line 3-3 of Fig. 1. Fig. A represents a verticalsection through the structure intersected by line 4-l of Fig. 3. Fig. 5represents a vertical section through the structure intersected by line55 of Fig. 3. Fig. 6 represents an elevation, partly in section, ofdetails adja cent line (36 of Fig. 3. Fig. 7 represents an elevation, asviewed from left to right,

of spring coupling device shown at the extreme left of Fig. 2. Fig. 8represents an elevation of a single cantaliver spring structureembodying the invention. Fig. 9 represents a vertical section of thestructure in tersected by line 99 of Fig. 8.

The same reference characters indicate the same parts wherever theyoccur.

Referring to Figs. 1 to 7 which relate to one form of the invention asapplied to a vehicle, wheel axles are indicated at 10 and 11respectively and two of the wheels are indicated at 12, 12. AlthoughFig. 1 shows only portions of two wheels, it is to be understood thatthis vehicle structure is intended to include four wheels. A steeringknuckle of suitable structure and arrangement is indicated at 13.

Fig. 1 includes'a load-sustaining frame which comprises longitudinalmembers 14, 14, and a series of transverse members 15, the members letand 15 being rigid with relation to each other. This frame is supportedby springs 16 and 16 at one end and by springs 24 and 24 at the otherend. As shown by Fig. 2 the springs 16 and 16 are connected to theload-sustaining frame by pivot studs 17 and 17 respectively and areconnected with the axle 11 by a coupling de' vice 19 and pivot studs 18and 18. A saddle, indicated at 20 in Fig. 2, is aflixed to theload-sustaining frame and has portions which rest respectively on theupper leaves of the springs 16 and 16. The details of this saddle 20 aresimilar to those shown by Fig. 5, this figure, however, being related tothe structure shown by Fig. 3 rather than to that shown by Fig. 2. Thespring-engaging portions of the saddle included in Fig. 2 are similar tothose indicated at 21 and 21 in Fig. 5. The parts 17, 17, and the saddle20, or some structure having a like function, comprise the anchoragebetween the springs and the vehicle frame. With this anchorage noprovision for taking up downward thrust or rebound is required, becauseof the action of the abutment or thrust member 22, which I locate on theframe, as hereinafter described.

The mounting of the springs 24: and 24c is, to all intents and purposes,the same as that of the springs 16 and 16. As shown by Fig. 3 thesprings 24: and 24. are connected to the load-sustaining frame by pivotstuds 25 and 25 and are connected to the axle 10 by a coupling device 27and pivot studs 26 and 26'. The saddle 20 included in Fig. 3 andotherwise shown by Fig. 5 is afiixed to the load-sustaining frame, andits portions 21 and 21 rest upon the upper leaves of the springs 24 and24'.

The duplex spring arrangement shown by Figs. 2and 3 is optional and isbut one specific embodiment of this invention, as will be understoodafter further explanation. The feature of this invention which isembodied in each modification shown is the provision of means arrangedto keep a portion of the spring structure deflected from its normalposition and at the same time leave another portion free to vibrate.Figs. 2, 3 and 6 illustrate abutments 22 which are arranged to engagethe springs for the purpose stated. These abutments are preferablycomposed of suitable soft material, such as rubber, in order to avoidnoise due to rattling. The elements 22 are carried by brackets 23, whichbrackets are aflixed to the load-sustaining frame. The dotted linesincluded in Figs. 2 and 3 indicate approximately the curvature which thesprings would assume when supporting a relatively light load if theabut-ments 22 were omitted. These abutments keep the springs deflectedfrom their normal position but do not prevent greater deflection due toan excessiveload. For example, when the load upon the springs exceedsthe force exerted on the springs by the abutments, the springs are freedfrom the abutments. The phrase critical load will be used to mean a loadwhich isjust suliicient to relieve the abutments 22 from the pressure ofthe springs, without separating the springs from the abutments; When thesprings are supporting a. load less than the critical load, asubstantial portion of the spring length is not used. In this case theportion of the spring length which is free to vibrate inchides (Fig. 2)the spring 16 and that portionzof 16 which is between the abutment- 22vand the axle 11, while of the structure shown by Fig. 3 the springstructure which is free to vibrate is the spring at and that portionofspring 2% which is between the abutment 22 and the axle 10. Theportions which are not free to vibrate under the condition last namedare that portion of spring 16' between the abutment 22 and saddle 20 andthe corresponding portion of spring 24 in Fig. 3. From this explanationit may be seen that one effect of the abutments 22 is to preventvibration of a portion of the spring length when the load is less thanthe critical load. In this connection it is to be observed that therelatively limber portions and not the relatively stiff portions of thespring structure are the ones which are free and active when supportinga load lighter than the critical load.

Fig. 8 shows a spring structure equivalent in some particulars to thatshown by Fig. 2, excepting that a single spring is shown instead of theduplex spring. In Fig. 8 the spring 16 is connected to the load-sustaiiring frame 11 by a pivot stud 17*, and is connected to a coupling device19 by a pivot stud 18*. The hanger is carried by the axle l1. 20indicates a saddle which is aliixcd to the frame ll and rests upon thetop leaf of the spring. 22 indicates an abutment which is, to all.intents and purposes, equivalent to that hereinbefore described. Thisfigure, however, shows the abutment 22 mounted in such manner as to beadjustable to vary the initial deflection of the spring. For thispurpose the abutment is provided with a screw stem 28 which is threadedin the bracket The bracket .is allixed to the frame M. It will be notedthat the form of my invention shown in Figs. 1 to 7 differs from F ig. 8generally in that the upper spring 16 of the double arrangementsuperimposes its effect upon that of the lower spring and supplementsthe action of the latter for both light and heavy loads. It enables theindividual springs to be made more flexible for the same load or enablesa greater load to be carried on individual springs of a given size.

The invention is not limited to springs extending longitudinally of thevehicle. It should be noted, however, that where the springs extendlongitudinally of the vehicle and are arranged as shown, the use ofaxlecarrying or axle-tortion rods, or other structures for performinglike functions, is made unnecessary, since these functions are performedby my improved spring construction in addition to the spring functions.

The use of this invention affords marked advantages in the case ofvehicles generally, and especially with automobiles when the roadsurface is irregular and the travel of the car is relatively rapid. Thefact that the spring 16 or l6 yields through only a portion of itslength in response to small irregularities in the road tends to reducethe amplitude and shorten the period of the vertical oscillationsacquired by the body. Under a load or impact exceeding the criti calload the remaining length of the spring, back of abutment 22 or 22 isautomatically brought into action and gives a cushioning effectproportioned to the increased stress. The transition occurs withoutshock or any abrupt increase of spring resistance; and since both endsare then under a tension corresponding to this critical load, the springis of course relatively stiff or resistant throughout its entire length.The. amplitude of the upward movement of the body which follows thisdeflection is materially lessened by the reseating of said spring on itsabutment, and it is an important advantage of my invention that itaccomplishes this checking of the rebound without requiring the use offrictional shock-absorbers, snubbing straps or similar devices.

Looked at in another way, the outer section of the spring 16 or 16 maybe regarded as corresponding to a vehicle spring of ordinary length,While the inner section is a reverse portion which adds to the effectivelength and cushioning properties of such spring in order to take care ofexcessive loads and. impacts, but which avoids the extreme rebound ofthe body experienced with an ordinary spring of corresponding totallength.

The adjustment of the abutment 22 provided in Fig. 8 enables the initialtension of the inner spring section to be regulated at will tocorrespond with the weight of the passengers or other load.

The use of a cantaliver or similar type of spring in connection with anabutment, such as 22, on the frame, having the functions mentioned,enables me to utilize and increase the well known easy-riding qualitiesof these springs without suffering the usual disadvantages of arelatively long spring, and at the same time it imposes the strain ofinitial deflection and rebound upon the frame, rather than upon theaxle, and avoids the necessity for any heavier construction of the axleor axle-attachment of the spring.

The difierence in lengths between the free portions of the springs 16,16,that is to say, the free portions of the spring 16 is that partbetween the pivot stud l8 and the saddle 20, while the free portion ofthe spring 16' when the latter rests on the abutment 22, is between saidabutment and the pivot stud 18,is such that when the spring 16 is clearof the abtuinent 22, both springs 16, 16 will have the same amplitude ofvibration; when, however, the abtument 22 engages the spring 16, thelatter will then have an amplitude or breadth of vibration less thanthat of the spring 16, with the result that the vibration of one springcounteracts that of the other. This feature of my invention, whilepresent in the duplex form shown in Figs. 2 and 3, for instance, wouldnot be present in the single form shown in Fig. 8. In both forms ofspring, however, the use of the abutment and the anchorage providesmeans for applying initial deflection to the spring in such a way thatthe latter is free of the influence of the abutment under loads orshocks in excess of the predetermined weight selected in each particularcase to give the desired permanent initial deflection.

Having thus explained the nature of my invention and described a way ofconstructing and using the same, though without attempting to set forthall of the forms in which it may be made, or all the modes of its use,what I claim and desire to secure by Letters Patent is 1. In a vehicle,the combination with a frame and a wheel-axle, of a leaf spring havingits inner portion anchored to the frame, and its outer portion attachedto the axle, and an abutment on the frame bearing against the'under sideof the spring inter mediate of its anchorage and its outer end, andserving to hold the inner section of the spring under a permanentinitial deflection.

2. In a vehicle, the combination with a frame and a wheel-axle, of aleaf spring tapered at both ends, the outer end being attached to theaxle and the inner end being attached to the frame, and the intermediateportion of the spring bearing upwardly against the frame, and anabutment on the frame, normally bearing against the under side of thespring between the said upwardbearing point and the axle and serving tohold the inner section of the spring under permanent initial deflection,while permitting the spring to yield as a whole to loads in excess ofthat represented by the initial deflection.

3. In a vehicle, the combination with a frame and axle, of twosuperimposed leaf springs anchored at their inner portions to the frameand attached to the axle at their outer ends, one of said springs beingnormally free to vibrate throughout its length, and an abutment on theframe bearing against the under side of the other spring intermediate ofits anchorage and its outer end and serving to hold the inner sectionthereof under a permanent initial deflection.

4. In a vehicle, the combination with a frame and axle, of twosuperimposed leaf springs, the outer ends of said springs being attachedto the axle, and the inner ends to the frame, and the intermediateportion bearing upwardly against the frame, and an abutment on the framenormally bearing against the under side of one of said springs betweenthe said upward bearing point and the axle, and serving to hold theinner portion thereof under a permanent initial deflection.

5. In a vehicle, the combination with a frame and a wheel-axle, of twosuperimposed leaf springs, the outer ends of said springs being attachedto the axle, and the inner ends to the frame, and means for subjectingthe inner portion of one of said springs to a predetermined initialcompression, said means being arranged to automatically release saidaction on said spring when said frame is subjected to loads or shocks inexcess of said initial compression and to antomatically establish andmaintain said initial compression when said loads or shocks do notexceed said initial compression.

6. In a vehicle, the combination with a frame and a wheel-axle, of aleaf-spring anchored on one of said members and having its free endattached to the other member, and an abutment on the first said 1nemberbearing against one side of the spring, intermediate of the anchorageand the free end of the latter, and serving as a stop to hold thatportion between the anchorage and the abutment under a permanent initialdeflection, the spring being free to flex under maximum load throughoutsubstantially its 3,

Copies of this patent me? be obtained for five cents each, by addressingthe Commissioner of Patents.

= Washington, D. G.

